Brake shoe grinder



March 27, 1934. R. E. w. HARRISON ET AL BRAKE snom GRINDER Filed May 14,1929 4 Sheets-Sheet 1' dttozmq March 1934- R. E. w. HARRISON ET AL1,952,130

BRAKE SHOE GRINDER Filed m 14, 1929 4 Sheets-Sheet 2 v Sunk-Sheet a N21; 72

BRAKE SHOE GRINDER Filed May 14. 1929 R. E. w. HARRISON El Al.

. March 27,1934.

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BRAKE SHOE GRINDER Filequa 1 4, 1929 I 4-Sheets-Sheet 4 gwumtou PatentedMar. 27, 1934 PATENT OFFICE BRAKE SHOE GRINDER Robert E. w. Harrison andFre Mount Washington, Ohio,

nati Grinders Incorpo corporation of Ohio :rick S. Haas, assignor toCincinrated, Cincinnati, Ohio, at

Application May'H, 1929, Serial No. 363,080

.3 Claims.

This invention relates to improvements grinding machinery and hasparticular referen to automatic mechanism for cyclic performance ofcylindrical grinding operations.

One of the objects of the present invention is the provision of animproved mechanism capable of automatic productionof arcuate orcylindrical surfaces simultaneously on a series of rings or segmentalportions thereof.

A further object of the invention is the provision of an automaticcontrol mechanism for a grinding machine of the center or work-chuckedtype which shall effect both the rotation of the work, the relative feedduring grinding andthe retraction and discontinuance of rotation of thework.

An additional object of the present invention is the provision of animproved work holding and driving mechanism which will greatlyfacilitate so the grinding of brake shoe or other segmental members andinsure uniformity of size and consequent interchangeability oftheseveral work pieces. 1

Other objects and advantages of the present invention should be readilyapparent by reference to the following specification, considered inconjunction with the appended drawings forming a part thereof, and itwill be understood that any modifications may be' made in these specificstructural details, hereinafter described, within the scope of theappended claims without departing from or exceeding the spirit of theinvention.

Figure 1 is a front view of a machine embodying the present invention.

Figure 2 is a top pian'view thereof.

Figure 3 is an enlarged fragmentary end view of the work holding memberand associated parts with the guard broken away as at line 3-3 of Figure2.

Figure 4 is a sectional view as on line 4-4 of Figure 3.

Figure 5 is a plan view of one of the work pieces.

Mare 6 is a view in elevation thereof.

Figure 7 is a plan view of the automatic cycle control mechanism withthe. enclosing casing therefor broken away.

Figure 8 is a vertical section as on line 8-8 of Figure 7;

Figure 9 is a section at right angles to Figure 8 on line 9--9 of Figure7.

Figure 10 is a longitudinal section on line 10-10 of Figure 7. and

Figure 11 is a section through the manual control device on line 11-11of Figure 9.

In the drawings, in which similar character references are employed'todescribe corresponding parts throughout the several views, the nu- 0meral 15 designates the bed of a grinding machine having risingtherefrom the grinder head 16, in which is suitably journaled thegrinding wheel spindle 17 bearing a grinding wheel 18. This spindle issuitably driven at a highor grinding rate of speed as from motor'19 andin addition is capable of an axial sliding or reciprocating movement inits bearings, under influence of the spindle oscillator mechanismindicated at 20. It is to be understood that this is preferably arelatively slight movement but servesto break up possible grinding lineson the work and insure a clean finish with minimum and equalized wheelwear.

Thebed 15, as indicated in Figure 1, is further provided with ways 21for the reciprocable carriage 22 hearing the work supporting unit. Thisunit includes a head 23, which has suitably mounted thereon thework-chuck supporting spindle 24 driven at a slow work revolving rate asfrom motor. 25. This spindle'has a plane laterally projecting terminalportion 26 disposed in opposition to the operative face of the grindingwheel 18 and is adapted to receive the sleeve portion 27'of the workholding fixture. This fixture has at one end the terminal flange 28seating against the rib 29 on the work supporting spindle, the partsbeing secured in inter-engaged relation as by pin 30 on the spindle,inter-fitting with bayonet slot or groove 31 of sleeve 27.

In the particular form illustrated, sleeve 27 has slidably mountedthereon a series of work clamping dis'cs having central hub portions 32,webs 33 and terminal flanged rims 34'. These parts are normally urgedinto spaced relation by interposed springs 35 but are capable of generalretraction for proper clamping of the several work pieces by tighteningnut 36 on the end of the sleeve. At suitable points'circumferentially ofthe rims 34, sockets 37 are provided for the spring pressed positioningpins 38. These pins are adapted to seat in the toggle holes 39 of thesegmental work pieces whichare here illustrated as internal brake shoeshaving the inner web or flange 40 and the circumferential shoe portion41 normally contacting, either directly or through intervention of asuitable lining, with the interior of a brake drum. To insure properoperation of the brakes of an automobile, it is necessary that thesemembers be true circular segments as respccts the arc positiondetermined in the drum by the toggle or supporting pins fitting in holes39.

By employment of the present mechanism, these segmental members may beplaced in overlying relation to the clamp discs with their webs pressedinto spaces between adjacent discs until the positioning pins38 snapinto holes 39, retaining the shoe proper .41 out of contact with theretaining discs. With the parts in this position, tightening of nut 36causes the clamps to laterally engage the webs of the work pieces sothat they are satisfactorily positioned in circumferential relation tothe arbor or work supporting fixture and thus to the spindle 26 in aposition determined, not by the original general contour of the workpiece but determined by the location of the apertures 39, which willsimilarly subsequently determine the position of the individual workpieces when in use.

.In the production of a series of ground work pieces it is desirablethat the work supporting spindle be located a sufficient distance fromthe grinding wheel so that the operator may, with safety, remove onework holding fixture and apply another having the rough or unground workpieces thereon. The work having thus been placed in the machine, it isthen desirable that the same be rapidly advanced to grinding position,be suitably rotated with a relative feeding movementbetween the work andgrinding wheel for proper stock removal, after which the .work shouldagain be withdrawn and its rotation discontinued in order that theoperator may remove the completed work and again insert new work to beground. One mechanism, for automatically controlling the aforesaid cycleof operations,

' has been illustrated in Figures 7 to 11 inclusive.

Carried by the bed 15' is a bracket 42 supporting a'housing 43. Joumaledwithin this housing is cam shaft 44 hearing the cam member 45 and theworm gear 46 in driving engagement with worm 4'7 activated from gearing48 by control motor 49. Cam 45 is loosely mounted on shaft 44 andcoupleable therewith through clutch 50 having a spool portion 51 engagedby shifter arm 52.

'Thearm is intermediately pivoted and has its opposite' 'end' riding ingroove 53 of sleeve 54 slidable in boss 55 ofthe casing unit 43. Thissleeve is provided with a rack 56 meshing with pinion 5'1 aduable byhand lever .58 for retracting or outwardly shifting the sleeve to moveclutch unit into operative position to,drive the cam 45. Movement in theopposite or declutching direction is automatically effected by means ofcompression spring 59., v

,The mechanism here described is intended to function as a singlerevolution clutch. For this purpose, there is slidably'mounted withinsleeve 54 a plunger 60 having a detent head 61, which in stop positionfits into notch 62 in the face of the cam member and interlocks with thecam to secure same against rotation. When handle 58 is shifted toretract sleeve 54, it carries with it the .detent 61, so thatthe cam isreleased and clutch 50 engaged. Rotation of the cam carries notch 62 outof alignment with head 61, when the head will ride on the face of thecam, holding the clutch in'engaged position until the camhas made acomplete revolution, when the detent member dropback into the notchunder influence of spring 59, the clutch being disengaged and the camrotation positively checked by the detent.

It is to be noted that the plunger 60, itself, i yieldingly mounted inthe sleeve and urged osareo into extended position by spring 63, havinga heavier tension than spring 59, so that the detent normally projects.In case of undue resistance to movement of the cam, however, spring 63will yield, allowing clutch 50 to slip and thus prevent breakage ofparts. The plunger is further provided with an extension, as at 64,which serves, as the plunger and sleeve are outwardly moved, to engageswitch member 65, completing the circuit between lead 66 and 67 of thedrive motor 25 for the work supporting spindle. Consequently, whenhandle 58 is manually actuated, to initiate rotation of cam 45, switch65 will also be actuated to start rotation of the work holding spindle.Conversely, when the machine is automatically brought to a stop bymovement of detent 61 into notch 62 of the cam, the work drive will berendered ineflective, spring 65 reversely shifting the switch member 65so that the work holding arbor member may be readily removed fromthemachine and a-new one substituted.

Cam 45 serves to control the operative association of the work andgrinding wheel. This is accomplished through employment of suitablelinkage mechanism including an interme-' coupled with slide block '14,in which is journaled adjusting screw 75 in threaded engagement with abushing '76 carried by the carriage 22. Oscil lation of lever 68, aseffected by the cam, causes a reciprocation of slide block '74 and thusof the screw and the work carriage. In addition, rotation of the screwby pilot wheel 7'7 adjusts the position of the work carriage withrespect to the block and, thus, the space traversed by reciprocations ofthe same amplitude, while the adjustment at '71 varies the amplitude ofthe reciprocations for a given cam contour.

The general outline of the activating cam groove 70 is indicated inFigure 8, from which it will be seen that the cam has a steepaccentuated portion, as at 78, for effecting a sharp retraction and,subsequently, a sharp or rapid inward movement of the carriage, thisportion controlling the movement of the parts in the work dischargingposition and initiating their .return movement into grinding relation.The camis further provided with a gradually receding portion, as at79,'controlling the feed or general ap- This portion 80 merges into theriser '78 for rapid retraction or separation. The riser 78 is disposedin opposition to notch or recess 62, so that, as the lever 68 is swungto its position of maximum retraction, the rotation of the cam and thedrive of the Work supporting spindle will be automatically discontinuedby the mechanism previously described. The machine is then in conditionfor removal of the holder with series of completed work pieces, andsubstitution of a new set of pieces to be ground. Inward oscillation ofhandle 58 will then disengage the cam, couple the clutch thereto foractuation thereof, and complete the work drive circuit for actuation ofthe work.

While in the present embodiment oi the invention, the cam 45 has beenshown as connected with'carriage 22 to impart a direct reciprocatingmovement to the carriage for varying the position of the work withrespect to the grinding wheel, it could, if preferred, be similarlyconnected with the grinding wheel, with the work holder spindle, or, therelative approach and separation of the parts could be efiected by anoscillatory movement of the grinding wheel or work holder support, underinfluence of the cam, without appreciably varying the general mechanismor result attained thereby, and these alternatives are thereforereserved as falling within the'preview of the present invention.

The operation of the device is as follows: The work rotating and feedingunit is normally in a retracted position, that is, remote from thegrinding wheel and with the work carrying spindle quiescent. The'sleeve2'7 having-previously had the work pieces mounted thereon is disposed onthe free end of the work spindle and the interlocking pin and slotengaged to prevent .disassociation of the sleeve and spindle. The leveror handle 58 is then actuated in a direction to initiate-the rotation ofthe motor 49, and parts operated thereby. This motor rotates the cam 45and efiects the .infeed of the work toward the grinding wheel, and atthe same time the operation of the handle 58 initiates the rotation ofthe work carrying spindle. The cam 45 feeds the work into the grindingwheel for a given definite distance, whereupon the work is retracted toits initial loading and unloading position. As soon as the work reachesits retracted position the motor 49 is stopped as well as the cam 45,thereby bringing the parts to a point -i'or a replacement of the work onthe work carrying spindle.

During the feeding and grinding cycle a sec-' ond work carrying sleeve2'7 is being loaded with work pieces so that as soon as the cycle iscomplete the operator replaces the sleeve on the spindle with a new onecontaining the unfinished work pieces, During the operation on the workon the second sleeve the finished work on the first sfeeve is removedtherefrom and replaced by other unfinished work pieces.

We claim:

1. In a device of the class described the combination of a bed, a pairof spindles journaled thereon having their axes extending parallel toone another and having free ends projecting in the same direction, agrinding wheel'secured to the end of one of the spindles, worksupporting means detachably secured to the end of the other spindle,means for rotating the grinding wheel at a high rate of speed, means forrotating the work supporting spindle at a relatively slow work rotationspeed, means supporting one 01 the spindles for movement toward and fromthe other and operable in the other direction for opening the switch andrestraining the cam against rotation. 1 2; In a device of the classdescribed the comthereon having their axes extending parallel to oneanother and having free ends projecting in the same direction, agrinding wheel secured to the end of one of the -spindles,'worksupporting means detachably secured to the end of the other.

spindle, means for rotating the grinding wheel at a high rate of speed,means for rotating the work supporting spindle at a relatively slow workrotation speed, means supporting one of the spindles for movement towardand from the other to operatively associate the work and grinding wheeland effect a stock removal from the work including a rotatable cam aprime mover for rotating the cam, a switch for controlling the workrotation means, a switch plunger operable in one direction to close theswitch and release the cam and operable in the other direction foropening the switch and restraining the cam against rotation, andadditional means operable by the switch plunger for connecting anddisconnecting the. rotatable cam from the prime mover. 3. In a device ofthe class described the combination of a bed, a pair of spindlesjournaled thereon having their axes extending parallel to one anotherand having free ends projecting in the same direction, a grinding wheelsecured to the end of one of the spindles, work supporting meansdetachably secured to the end of the other spindle, means for rotatingthe grinding wheel at a high rate of speed, means for rotating the worksupporting spindle at a relatively slow workrotation speed, meanssupporting one of the spindles for 'movementtoward and from the other tooperatively associate the work and grinding wheel and effect a stockremoval from the work including a rotatable cam, a prime mover forrotating the cam, a switch for' controlling the work bination of a bed,a pair of spindles journaled rotation means, .a switch plunger operablein one tion means for shifting the switch plunger in one direction andyielding means for shifting the said plunger in the other direction.

ROBERT E. w. HARRISON. FREDERICK s. HAAS.

